A cool solution on Lake Michigan

A rock tunnel extending under Lake Michigan provides cooling water to the Oak Creek and Elm Road power plants.

Opportunity

The Oak Creek Power Plant, 20 miles (32 kilometers) south of Milwaukee on the shore of Lake Michigan, generates 1,135 megawatts of power from four coal-fueled steam turbines.

In 2010 and 2011, We Energies added two power units at the nearby Elm Road Generating Station, providing an additional 1,230 megawatts.

Solution

Mott MacDonald designed the shafts, tunnel, and other infrastructure for a lake-water intake system capable of supplying 2.2 billion gallons a day (8.3 million cubic meters) to the Oak Creek and Elm Road plants.

A tunnel with a finished interior diameter of 25 feet (8 meters) was excavated through 1.75 miles (2.8 kilometers) of rock. Four steel-lined intake shafts 12 feet (3.7 meters) in diameter were constructed.

Outcome

The new system provides a robust supply of cooling water for the power plants. Wedgewire screens made of a special alloy keep zebra mussels from fouling and entering the water intakes — a constant problem on the Great Lakes.